(1) Field of the Invention
This invention relates to a system for the formation of a continuous, cylindrical, elongate body composed of a resilient tape-like material which is helically wrapped to generate the cylindrical body. The wrapping may be carried out to generate a hollow body or may be executed in conjunction with a solid continuous cylindrical or filamentous core member to cause the core member to become helically wrapped in, and therefore sheathed by, the tape-like material.
(2) Description of the Prior Art
The wrapping of continuous elongate bodies, such as wires, cables and ropes, is well known and uses a wide variety of materials and wrapping geometries and techniques. For example it is well known to wrap electrical cables with paper tape for insulating purposes by employing planetary reels adapted to lay the paper tape helically, with or without overlap, so as to provide one or more layers of insulation. Generally additional agents are employed such as glues, sizes and varnishes.
However in some applications, particularly those not involving the paper tape primarily as an electrical insulator, the wrapping of a filament core with paper tape is highly desirable for a number of reasons. For example, during the past twenty years or so there have been a number of efforts made to manufacture woven fabric for wool bales from materials which would overcome the problem of contamination of wool by these materials. This objective can be achieved if these materials are either removed in the processing or do not show as faults in the finished wool fabric. Nylon is a material which accepts wool dyes and if it is in the form of a fine filament it is not visible as a fault in the wool fabric. Paper is another material which does not become a contaminant as it is removed in processing.
Wool bales have been woven from nylon multifilament yarns but they suffer from several disadvantages. A nylon pack which has just sufficient tensile strength to meet the extreme stresses encountered in dumping tends to stretch under the relatively low levels of stress which exist when it is fully loaded and hence bulges unduly. Using appreciably higher fabric weights of nylon overcomes the bulging problem but then the cost becomes prohibitive. Moreover nylon's low coefficient of friction leads to difficulties in stacking the loaded bales due to the tendency of the bales to slip and topple.
Wool bales have also been woven from twisted paper yarn, but because of its low tensile strength, it must have a high linear density with the result that a bale to meet the required strength becomes heavy and stiff. However, it does have the required stiffness characteristics for good shape retention.
Due to the perceived non-contaminating advantages in weaving bale fabrics from paper/nylon composite yarns, namely the potential to combine the high strength of nylon multifilament with the high stiffness of paper, one of the present inventors has described the results of investigations carried out to this effect; see R. E. Belin, "Wool Packs made from a Paper/Nylon Wrap Yarn", Textile Institute and Industry, (Aug. 1981), pp. 229-230. This yarn comprised a nylon core around which a paper tape was helically wrapped so that each turn overlapped the previous one to ensure complete coverage of the core. This was achieved using a standard flyer cone rover modified by the removal of the drafting units and with the addition of creels for nylon and for paper, means for moistening the paper tape and a yarn forming device. However, special provision of means to deliver the paper under constant tension was required and the yarn forming device was difficult to thread. In addition, yarn production rate/spindle was low, about 15 m/min., because of the limitation in twisting speed of this type of machine.